JPH08248740A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device capable of forming a high-quality image by removing the soiling such as vertical streak of an electrifying roller in a circumferential direction. CONSTITUTION: This image forming device provided with an image forming part executing such a process that an electrostatic latent image is formed on the surface 1a of a photoreceptor 1 electrified by being brought into contact with the electrifying roller is provided with the photoreceptor 1 turned by carrying the electrostatic latent image, the electrifying roller 2 for electrifying the photoreceptor 1 by being brought into rotational contact with the surface of the photoreceptor 1, a cleaning member 3 for cleaning the surface of the roller 2 while being in contact the roller 2 by being moved along in the shart direction of the roller 2 and a moving means 4 for moving the cleaning member 3 in the shaft direction of the roller 2 when the rotating action of the roller 2 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, a printer, a scanner, or a multi-function machine having these functions together, and more particularly to a rotating drum or belt. And an image forming apparatus including an image forming unit for forming a toner image on an electrostatic latent image formed by irradiating an electrostatic latent image formed by irradiating an original reflected light or the like on the surface of a photoconductor Is.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus such as a copying machine, a facsimile machine, a printer, a scanner, or a multi-functional machine having these functions, a surface of a photosensitive member to be charged is a corona charging device. The image is formed by uniformly charging the toner to form an electrostatic latent image. When using this corona charging device, along with corona discharge,
Since ozone and nitrogen oxides are generated, they may be harmful to the human body and the environment, or may have a bad influence on the environment. However, there is a problem that the device is large and expensive. Furthermore, there is a risk that ozone and nitrogen oxides generated by corona discharge may adhere to the photoconductor, charger, optical system and other parts in the electrophotographic copying machine, causing image deterioration. There was also.

Therefore, a contact charging type charging device and an electrophotographic device are proposed in which ozone or nitrogen oxide is scarcely generated and a charging member to which a voltage is applied is charged in a state of being brought into contact with a photosensitive member which is a member to be charged. Have been known (Japanese Patent Application Laid-Open No. 6-58242)
(See the official gazette of 3-149668). Such a contact charging type charging device can improve the charging efficiency because the applied voltage required to obtain a desired charging potential on the surface of the photoreceptor to be charged can be reduced, and thus the charging efficiency can be improved. Since the member is in contact with the photoconductor, the toner remaining when the surface of the photoconductor is cleaned by the cleaning unit after the toner image formed on the surface of the photoconductor is transferred to the transfer paper is charged by the charging member. However, there is a problem in that the toner adheres to the surface of the charging roller and causes a charging failure, which causes uneven charging, image blurring, and abnormal images such as white streaks and black streaks.

Therefore, in order to prevent the occurrence of abnormal images such as white streaks and black streaks by the contact charging type charging device, a cleaning member made of a felt material is brought into contact with the charging roller to clean the surface of the charging roller. Such a technique is also known (see Japanese Patent Application Laid-Open No. 2-272582). There is also known a technique in which a cleaning member made of foamed polyurethane or polyethylene is always brought into contact with the charging roller (see Japanese Patent Application Laid-Open No. 3-101768). Alternatively, there has been proposed a charging roller in which a cleaning member can be brought into contact with and separated from the charging roller.

However, in any of these conventional cleaning devices for a charging member such as a charging roller, the charging member is rotated while the cleaning member is in contact with the entire or a part of the longitudinal direction of the charging member. By doing so, the surface of the charging member is cleaned, so that stains such as vertical stripes easily occur in the circumferential direction of the charging member, and as a result, the quality of the formed image deteriorates. Further, when the cleaning member of the charging member is deteriorated and the cleaning performance is deteriorated, the amount of toner adhered to the surface of the charging roller becomes non-uniform, so that cleaning failure occurs in the circumferential direction of the charging member and an abnormal image is generated. There was also the problem of being formed.

[0006]

In the above-mentioned conventional image forming apparatus, there is a problem that the quality of the formed image is deteriorated by dirt such as vertical streaks in the circumferential direction of the charging roller.

[0007]

An object of the present invention is to solve the above problems and to provide an image forming apparatus capable of forming a high quality image by removing dirt such as vertical stripes in the circumferential direction of a charging roller. The purpose is to do.

[0008]

In order to achieve the above object, the present invention according to claim 1 executes a step of forming an electrostatic latent image on the surface of a charged photoreceptor by bringing a charging roller into contact therewith. In an image forming apparatus including an image forming unit, a photoconductor that carries an electrostatic latent image and rotates, a charging roller that charges the photoconductor by rotating contact with the surface of the photoconductor, and the charging roller. A cleaning member that comes into contact with the surface of the charging roller to clean it when moving along the axial direction of the charging roller, and a moving means that moves the cleaning member in the axial direction of the charging roller when the charging roller is stationary in rotation. And having. According to the invention of claim 2,
The moving means reciprocates the cleaning member in the axial direction of the charging roller. The invention according to claim 3 is characterized in that the moving means changes a speed at which the cleaning member is moved in an axial direction of the charging roller. According to a fourth aspect of the invention, the cleaning member is separated from the surface of the charging roller when not being cleaned.

[0009]

According to the first aspect of the invention, since the cleaning member is moved in the longitudinal direction of the charging roller by the moving means when the rotation operation of the charging roller is stationary, vertical stripes or the like in the circumferential direction of the charging roller are generated. It is possible to remove stains and perform high quality image formation. In the second aspect, the cleaning member is reciprocally moved in the longitudinal direction of the charging roller by the moving means when the rotation operation of the charging roller is stationary. Therefore, dirt such as vertical stripes in the circumferential direction of the charging roller can be efficiently provided. It can be removed to form a high quality image.

According to the third aspect of the present invention, the cleaning member is moved by the moving means at a variable speed in the longitudinal direction of the charging roller when the rotation operation of the charging roller is stationary. It is possible to remove stains such as streaks more efficiently and in a short time to form a high quality image. According to the present invention, the cleaning member is moved in the longitudinal direction of the charging roller by the moving means when the rotating operation of the charging roller is stationary, and is moved away from the surface of the charging roller when the cleaning member is not cleaned. As a result, stains such as vertical stripes in the circumferential direction of the charging roller can be removed for a long period of time to form a high quality image.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a main part of an image forming apparatus according to an embodiment of the present invention. This electrophotographic copying machine includes a drum-shaped photoconductor 1 that rotates in the direction of arrow A at a predetermined peripheral speed, and a charging roller 2 that rotates along with the photoconductor 1 and is driven to rotate in the direction of arrow B at a constant speed. A cleaning member 3, a photoconductor driving device 5, a conductive pressure spring 6, an exposure unit 7, a developing unit 8, a transfer separation unit 9, a cleaning unit 10, and the like. The surface 1a of the photoconductor 1 is brought into contact with the surface 2a of the charging roller 2 so that a predetermined potential is uniformly charged.

The photoconductor 1 is rotatably driven by a photoconductor drive device 5 including a drum drive timing belt, a drum drive pulley, a motor for driving them, and the like, and a charging roller 2 is provided on the surface 1a of the photoconductor 1. Surface 2a
However, due to the biasing force of the conductive pressure spring 6, for example, the contact pressure per unit length is 10 g / cm. The conductive pressure spring 6 is supported by the device body side. In addition to the charging roller 2, an exposure unit 7, a developing unit 8, a transfer / separation unit 9, a cleaning unit 10, and the like are arranged around the photoconductor 1, and these constitute an image forming unit.

The surface 1a of the photosensitive member 1 is charged by being uniformly charged to a predetermined potential by the charging roller 2 which is in rotary contact, and the original image read by the reading means (not shown) is exposed by the exposing means 7. As a result, an electrostatic latent image is formed. When the electrostatic latent image on the photoconductor passes through the developing unit 8, the electrostatic latent image is visualized by the toner 11 supplied by the developing sleeve 8a and passes through a pre-transfer charge eliminator (not shown). To the transfer position (the position where the transfer / separation unit 9 is arranged) where the transfer is performed on the sheet 12 from.

The sheet 12 to which the visualized toner image is transferred is fed from a sheet feeding cassette (not shown) in the direction of arrow C shown in the figure, and a pressure roller 13a and a driving roller forming a registration roller pair 13 are formed. It is conveyed to a stop position where it is temporarily stopped with the tip abutting on the nip portion with 13b. The sheet 12 conveyed to the stop position of the registration roller pair 13 reaches the transfer position where the transfer separation unit 9 is located in synchronization with the movement timing of the toner image formed on the surface 1a of the photoconductor 1 by the registration roller pair 13. After being sent and receiving the transfer of the toner image, the charge is removed, the surface is separated from the surface 1a of the photoreceptor 1, and the toner is conveyed to the fixing device 14 by a conveying unit (not shown). After the toner image is fixed by the fixing device 14, the toner image is ejected from the ejection roller 15a of the ejection unit 15 and accommodated in the ejection tray 15b.

On the other hand, at the transfer position of the transfer separation unit 9,
After the toner image is transferred onto the sheet 2, the surface 1a of the photoconductor 1
The cleaning blade 10a provided in the cleaning unit 10 scrapes off and removes the remaining foreign matter such as toner and paper dust, and the pre-charging static eliminator (not shown) neutralizes the residual potential. The charging roller 2 is prepared for charging when the next image forming process is started.

The charging roller 2 is integrally provided with a conductive rubber roller portion 2c made of, for example, EPDM (ethylene propylene diene terpolymer) or ECO (hydrin rubber) on the outside of a conductive cored bar 2b made of iron or the like. Both ends of the conductive cored bar 2b are rotatably supported by the conductive bearings 16, and the conductive bearings 16 are urged by the conductive pressure springs 6 toward the surface 1a of the photoconductor 1. Because
The axis of the charging roller 2 itself is in contact with the surface 1a of the photoreceptor 1 in a state where the axis of the charging roller 2 is parallel to the axis of the photoreceptor 1. The DC power source is, for example, a conductive pressure spring 6 as shown in the figure.
Between the DC power source 17 and the conductive pressure spring 6, which is arranged between the DC power source 17 and the conductive core metal 2b of the charging roller 2.
Also, the surface 1a of the photoconductor 1 is uniformly charged by applying the charging bias voltage via the conductive bearing 16.

A cleaning member 3 is provided on the surface 2a of the charging roller 2.
Is provided, and the cleaning member 3 is displaced by the moving means 4 by displacing the cleaning member 3 in the longitudinal direction of the charging roller 2 when the rotation operation of the charging roller 2 is stopped. The cleaning member 3 has a felt shape, a brush shape,
The material is blade-shaped, and the material thereof is ultrafine fiber, soft urethane foam, or Teflon fiber.

The control device 18 for driving and controlling various operations of the moving means 4 and the like in the apparatus is composed of a microcomputer, and has a central processing unit (CPU) having various judgment and processing functions and various operations. Which is a program memory that stores various programs and fixed data under the control for performing a predetermined timing
And a RAM which is a data memory for storing input data and processing data by the CPU, an input / output circuit (I / O), and the like.

The control device 18 includes a start key 19a of a control panel 19 provided outside the main body of the device.
Is input when the image forming operation is started, and an image forming start signal that is output is input. The control panel 19 is provided with another key group 19b for selecting image forming conditions such as the size of the paper 12 and the density of the transferred image. Various keys selected by operating these key groups 19b are transmitted. You can enter. Then, a signal for rotationally driving the photoconductor 1 is output to the photoconductor driving device 5 via the photoconductor driver 20 at a predetermined timing, and the image formation is performed each time image formation is performed. A signal can be output to the image forming number counting unit 21 that counts the number of times.

FIG. 2 is a perspective view showing the structure of an example of the moving means, and FIG. 3 is a cross-sectional view showing the structure of the main part thereof.
The rotational driving force of the motor 4a is transmitted to the screw-shaped feed screw 4e through the worm wheel 4b, the gear group 4c, and the joint 4d during cleaning, which is the stationary operation of the rotation of the charging roller 2, and rotates in the forward and reverse directions. It is like this.
The feed screw 4e has a support member 3a for supporting the cleaning member 3.
Are screwed together, and are configured to advance and retract in the axial direction by the forward and reverse rotations of the feed screw 4e. In this embodiment, the two feed members 3a are screwed in a state in which they are axially different from each other with respect to the single feed screw 4e, and the cleaning members 3 supported by the respective feed members 3a are screwed together. Laura 2 each
Facing different sides of.

When the control device 18 controls the rotation of the DC motor 4a, the cleaning member 3 is movable at a constant speed or at a variable speed in the longitudinal direction (axial direction) of the charging roller 2, so that the forward path can be moved. Alternatively, the cleaning can be efficiently performed by setting the optimum moving speed in accordance with the return path, the position where the surface 2a of the charging roller 2 is heavily soiled or the position where the surface is not heavily soiled.

When the feed screw 4e rotates in the forward and reverse directions, a cleaning member 3 for nipping and cleaning the charging roller 2 from the left and right is supported at one end, and the other end is screwed into the thread portion of the feed screw 4e. , Are displaced or reciprocally moved in the longitudinal direction of the charging roller 2 in the direction of the arrow D shown. After the support member 3a moves in the same direction, when the support member 3a stops at the home position at the left end, the right end, or both ends in the drawing, the cleaning member 3 is guided by the guide member 4f and separated from the surface 2a of the charging roller 2. (See FIG. 3).

The support structure of the cleaning member 3 by the support member 3a is such that the guide member 4f controls the direction of the support piece 3A integrally extending from the cylindrical support member 3a having the female screw formed on the inner peripheral surface thereof. To configure. When the cleaning member 3 (supporting piece 3A) reaches the home position, the cleaning member 3 is rotated by being changed in direction by the guide member 4f arranged along the feed screw 4e, and separates the cleaning member 3 from the charging roller. Further, when the guide member 4f is separated from the home position, each of the cleaning members 3 including the support member 3a is guided by the guide member 4f.
Since the direction of (3A) is regulated so as to rotate in the pressure contact direction, the surface of the roller 2 is pressure contacted for cleaning.

The guide member 4f is, for example, a plate-shaped or rod-shaped member arranged along the axial direction of the roller 2, or a guide formed on a plate arranged between the roller 2 and the guide member 4f. It is composed of slits, and when the support member 3a reaches the home position, the support member 3a is configured to rotate in the direction in which it is separated from the roller 2. As described above, the cleaning member 3 is arranged so as to be separated from the surface 2a of the charging roller 2 while the surface 2a of the charging roller 2 is not being cleaned. It is possible to prevent the occurrence of abnormal image quality due to poor cleaning due to deterioration of the cleaning member 3 and the cleaning member 3.

FIG. 4 is a schematic view of the essential portions of another embodiment of the present invention. The moving means 4 for moving the cleaning member 3 back and forth in the longitudinal direction of the charging roller 2 in the direction of the arrow D shown in FIG. The mechanism is not limited to the mechanism that rotates the feed screw 4e. For example, as shown in the figure, the support member 3 is attached to the wire 4h that is wound between the drive pulley 4g1 that is directly connected to the output shaft of the DC motor 4a and is driven to rotate, and the driven pulley 4g2.
By fixing a, the cleaning member 3 can be displaced or reciprocated in the longitudinal direction of the charging roller 2. Guide member 4f
Is turned in a direction away from the charging roller 2 (not shown) at a position corresponding to the home position, and the support member 3a slides along the turning portion. As a result, the cleaning member 3 can move in the direction away from the roller 2.

5 and 6 are end views showing the construction and operation of the main part of another embodiment of the present invention. In this embodiment, the length of the cleaning surface 3B of the cleaning member 3 in the circumferential direction is set to the charging roller 2. The characteristic is that the surface 2a is set so as to cover about 1/2 to 1/3 of the total circumference of the surface 2a. Further, since the guide member 3f closes the guide member 3f in the direction of the arrow E and then reciprocates repeatedly, the entire surface of the rotating charging roller 2 is cleaned.

The two support members 3a are independently screwed to the feed screw 4e while being adjacent to each other in the axial direction.
The two support pieces 3A, which reciprocate in the axial direction according to the forward and reverse rotations of the feed screw 4e, rotate in the E direction when each support member 3a rotates on the feed screw 4e. Can be brought into contact with or separated from the surface of the roller 2. In this embodiment, the guide member 4f is located outside the both support pieces 3A, and FIG. 5 shows the state in the home position. Therefore, the distance between the both guide members 4f and the roller 2 is wide. Guide member 4f shown in FIG.
The portion guides the support piece 3A including the support member 3a in the non-pressure contact direction. On the other hand, FIG. 6 shows a state in which the cleaning member 3 supported by the support piece 3A has a narrow space between the roller 2 and the guide member 4f. It is pressed against the roller 2 and cooperates with the rotation of the roller 2 to clean it.

FIGS. 7 and 8 are views for explaining the construction and operation of another embodiment of the present invention, in which the circumferential length of the cleaning member 3 is made longer than that of the cleaning member of the embodiment of FIGS. The difference is that the entire surface 2a of the charging roller 2 is covered. If there is a risk that the charging operation of the charging roller 2 will not be performed normally when the two support pieces 3A interfere with each other at the time of charging, the charging roller 2 is not shown in the drawing. You may make it move to the arrow F direction. That is, the lower surface of the charging roller (the surface facing the photoconductor)
The roller 2 may be lowered in the F direction at the time of charging in order to prevent the toner from being unable to contact the photoconductor.

While moving the charging roller 2 to the position shown in FIG. 7, the cleaning member 3 is guided by the feed screw 4e to the guide member 4f.
When it is moved from the non-home position along the direction, the support piece 3A closes in the direction of the arrow E to bring the cleaning member 3 into pressure contact with the charging roller 2. In this state, move the cleaning member in the axial direction,
Further, by rotating the charging roller 2, the entire circumference of the surface 2a of the charging roller 2 is cleaned.

Next, FIGS. 9 (a) and 9 (b) are a bottom perspective view showing the structure of the main part of another embodiment of the present invention and a plan view showing an example of the structure of the guide member. Then, a partition plate F made of sheet metal or the like is provided between the charging roller 2 and the feed screw 4e.
The partition plate F is formed with a single linear slit F1 and a forked slit F2 provided at a position corresponding to the home position. Since the linear slit F1 runs parallel to the position directly below the feed screw 4e, when each support member 3a is located in the non-home position, each support piece 3A enters the linear slit F1 and each cleaning member 3 Although pressed against the peripheral surface of the charging roller 2, when the home position is reached, each support piece 3A enters the bifurcated slit F2, and thus branches left and right, and the cleaning member 3 separates from the charging roller 2.

The movement of the moving means 4 during cleaning may be a one-way operation from one home position to the other home position, or a reciprocating operation of reciprocating. As a result, it is possible to efficiently remove stains such as vertical stripes in the circumferential direction of the charging roller and perform high quality image formation. Further, the moving means may control the speed at which the cleaning member is moved in the axial direction of the charging roller to be variable. As a result, stains such as vertical stripes in the circumferential direction of the charging roller can be more efficiently removed in a short time, and high-quality image formation can be performed.

[0032]

As described above, according to the first aspect of the present invention, the cleaning member 3 is moved by the moving means 4 when the rotation operation of the charging roller 2 is stopped.
Since the charging roller is moved to, the dirt such as vertical stripes in the circumferential direction of the charging roller can be removed and high quality image formation can be performed.

According to the second aspect of the present invention, since the cleaning member is reciprocally moved in the longitudinal direction of the charging roller by the moving means when the rotation operation of the charging roller is stationary, the longitudinal stripes in the circumferential direction of the charging roller are provided. It is possible to efficiently remove stains and the like to form a high quality image.

According to the third aspect of the invention, when the rotation operation of the charging roller is stationary, the cleaning member is moved by the moving means in the longitudinal direction of the charging roller at a variable speed. It is possible to more efficiently remove stains such as vertical stripes on the edges in a short time to form a high-quality image.

According to the invention of claim 4, the cleaning member is moved in the longitudinal direction of the charging roller by the moving means when the rotating operation of the charging roller is stationary, and is moved away from the surface of the charging roller when the cleaning is not performed. Is prevented, and dirt such as vertical stripes in the circumferential direction of the charging roller can be removed for a long period of time to form a high-quality image.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an outline of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a main part of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 3 is an enlarged view for explaining another main part of the embodiment of FIG.

FIG. 4 is a perspective view illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 5 is an enlarged view for explaining a state of a main part of another embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the embodiment of FIG.

FIG. 7 is an enlarged view illustrating a state of a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 8 is an operation explanatory diagram of the embodiment of FIG.

9A and 9B are a perspective view and a plan view of a main part of another embodiment.

[Explanation of symbols]

1 ... Photoconductor, 1a ... Surface, 2 ... Charging roller, 2a ... Surface, 2b ... Conductive core metal, 2c ...
・ Conductive rubber roller, 3 ... Cleaning member, 3A ...
Support piece 3a ... Support member, 4 ... Moving means, 4a
... DC motor, 4b ... Warm wheel, 4c
... Gear group, 4d ... Joint, 4e ... Feed screw, 4f ... Guide member, 4g1-2 ... Pulley, 4h ... Wire, 5 ... Photoconductor driving device, 6・
..Conductive pressure springs, 7 ... exposure means, 8 ... development unit, 8a ... development sleeve, 9 ... transfer separation unit, 10 ... cleaning unit, 10a
..Cleaning blades, 11 ... toner, 12 ...
..Paper, 13 ... Registration roller pair, 13a ...
Pressure roller, 14 ... Fixing device, 15 ... Paper discharging means,
15a ... Paper ejection roller, 15b ... Paper ejection tray, 1
6 ... Conductive bearing, 17 ... DC power supply, 18 ...
Control device, 19 ... Control panel, 19a ...
・ Start key, 19b ... Other key groups, 20 ...
Photoconductor driver, 21 ... Image forming number counting unit.

Claims (4)

[Claims] 1. An image forming apparatus equipped with an image forming unit for executing the step of forming an electrostatic latent image on the surface of a photoreceptor charged by bringing a charging roller into contact with the electrostatic latent image. The rotating photoconductor, the charging roller that charges the photoconductor by rotating while contacting the surface of the photoconductor, and the charging roller that moves in the axial direction while being in contact with the surface of the charging roller An image forming apparatus comprising: a cleaning member that cleans the surface; and a moving unit that moves the cleaning member in the axial direction of the charging roller when the rotation operation of the charging roller is stationary. 2. The image forming apparatus according to claim 1, wherein the moving unit moves the cleaning member back and forth in the axial direction of the charging roller. 3. The image forming apparatus according to claim 1, wherein the moving unit makes variable the speed at which the cleaning member is moved in the axial direction of the charging roller. 4. The image forming apparatus according to claim 1, wherein the cleaning member is separated from the surface of the charging roller when cleaning is not performed.